Laura and Marco Face Different Hazards Trying to Intensify

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Tropical Storm Marco is a little stronger at 8AM EDT Saturday. However, a 30-40 knot southwest upper shear band is ahead across the central Gulf of Mexico. Marco will need to fight through that shear to survive. Tropical Storm Laura is forecast to track west-west-northwest across Hispaniola and Cuba over-the-weekend which is a tough course to follow to survive due to the high terrain. HOWEVER, if each storm survives these obstacles the super warm Gulf of Mexico could allow strengthening to a hurricane before eventual landfall in the north or northwest Gulf of Mexico.

Highlight: Laura and Marco face different hazards trying to intensify.

Fig. 1: Upper shear axis analysis identifies a streak of 30-40 knot southwest shear across the Gulf of Mexico.

Fig. 2-3: The very warm Gulf of Mexico is warmer-than-normal.

 

Fig. 4-5: Tropical cyclone models tracks/intensity forecast for Laura.

Fig. 6-7: Tropical cyclone models tracks/intensity forecast for Marco.

Fig. 8: Tropical cyclone models tracks/intensity forecast for Marco.

Fig. 9: Tropical cyclone models tracks/intensity forecast for Laura.

Fig. 10: The NOAA/NHC 7-day rainfall forecast.

Fig. 11: Morning satellite view and Climate Impact Company projected tracks for Laura and Marco.

Discussion: Tropical Storm Laura is located near the south coast of Puerto Rico this morning. Laura is a MINIMAL tropical storm racing westward at 21 mph. Laura is forecast to move west to west-northwest across Hispaniola and Cuba over-the-weekend. There is a REAL risk this track will dissipate this storm. If Laura can remain intact entering the Gulf of Mexico early Tuesday the environment (less shear and very warm water) would enable intensification and minimal hurricane would strike the upper Texas coast Wednesday afternoon. The Gulf of Mexico forecast track and intensity for Laura is LOW confidence.

Tropical Storm Marco is disorganized and forecast tur turn into a strong southwest upper shear zone stretched across the central Gulf of Mexico this weekend. Surviving that upper shear will not be easy. But! Marco’s location over the warm Gulf water should enable survival. Marco turns west-northwest to the south of the subtropical high to the north and moves inland as a tropical storm in the Houston area Tuesday. There is a possibility that the upper shear could drag Marco northward early next week. The Marco forecast track is LOW confidence.

NOAA/WPC continues to forecast 5-15 in. of rain in the northwest/north/northeast Gulf of Mexico coast due to each storm’s arrival next week. These locations should plan on flooding rainfall for next week and at least tropical storm force wind.

Tropical cyclone models indicate 15-20% chance of a hurricane with Marco and about 40% chance of a hurricane for Laura. Forecast models are farther west with Laura (upper Texas coast) with two possible tracks for Marco.

The Gulf of Mexico is very warm and warmer-than-normal. If a low shear environment were present a major hurricane would develop. However, the upper shear pattern is quite impressive right now.

Two hurricanes in the Gulf at one time is difficult as hurricanes require a lot of atmosphere – well beyond the attendant cloud pattern – to develop. The chance of simultaneous hurricanes in the Gulf – meteorologically – is very low.